* denotes adult books

If you liked the Modern Faerie Tales series (Tithe, Valiant, and Ironside), you might like:

War for the Oaks, by Emma Bull*
Jack of Kinrowan, by Charles de Lint*
The Bordertown Anthologies, edited by Terri Windling (and of which Welcome to Bordertown was the most recent, edited by Ellen Kushner and myself)
Tripping to Somewhere, by Kristopher Reisz
The Perilous Guard, by Elizabeth Marie Pope
The Mortal Instruments, by Cassandra Clare
The Books of Faerie, by Maggie Stiefvater
The Wicked Lovely series, by Melissa Marr
The Iron Fey series, by Julie Kagawa
The October Daye series, by Seanan McGuire

If you liked the Curse Workers series (White Cat, Red Glove, and Black Heart), you might like:

The Westing Game, by Ellen Raskin
Heist Society, by Ally Carter
The Thief, Megan Whalen Turner
The Demon’s Lexicon series, by Sarah Rees Brennan

If you liked The Coldest Girl in Coldtown, you might like:

Team Human, by Sarah Rees Brennan and Justine Larbalestier
The Silver Kiss, by Annette Curtis Klaus
Interview with the Vampire, Anne Rice*
Sabella, or the Blood Stone, by Tanith Lee*
Lost Souls, by Poppy Z. Brite*
Sunglasses After Dark, by Nancy A. Collins*
The Vampire Tapestry, by Suzy McKee Charnas*

If you liked Doll Bones, you might like:

The Egypt Game, by Zilpha Keatley Snyder
From the Mixed-Up Files of Mrs. Basil E. Frankweiler, by E.L. Konigsburg
Coraline, by Neil Gaiman
The Wolves of Willoughby Chase, by Joan Aiken
The Doll in the Garden, by Mary Downing Hanh
The House with a Clock in its Walls, by John Bellairs
Harriet the Spy, by Louise Fitzhugh

If you liked The Spiderwick Chronicles, you might like:

A Tale Dark and Grimm, by Adam Gidowitz
Blackbringer, by Laini Taylor
The Five Children and It, by E. Nesbit
The Dark is Rising, by Susan Cooper
The Folk Keeper, by Franny Billingsley
The Princess and the Goblin, by George MacDonald
Inkheart, by Cornelia Funke
The Lightning Thief, by Rick Riordan
The Search for Wondla, by Tony DiTerlizzi

If you liked The folk of the air (The Cruel Prince, Wicked King, Queen of nothing), you might like:

And I Darken by Kiersten White
Forest of A Thousand Lanterns by Julie C Da
Winternight Trilogy (Bear and the Nightingale) by Katherine Arden
Ash by Malinda Lo
The Raven Cycle Series by Maggie Stiefvater
Darker Shade of Magic Series by Victoria Schwab